Guide wires are commonly used in minimally invasive procedures to guide catheters or other medical devices to a target site within the body. The guide wire can be advanced to the site, followed by advancing other medical devices such as guide catheters, therapeutic catheters, or diagnostic catheters, over the guide wire to the target site. Guide wires are commonly used in percutaneous transluminal coronary angioplasty (PTCA) procedures. In PTCA procedures, a guide wire can be inserted into the femoral artery of a patient near the groin, advanced over the aortic arch, further advanced into a coronary ostium, and thereafter into a coronary artery. A guide wire insertion procedure is typically performed under fluoroscopy, with the treating physician monitoring the guide wire distal end position within the patient. Examples of guide wires may be found in U.S. Pat. No. 3,973,556 to Fleischhacker et al.; U.S. Pat. No. 4,080,706 to Heilman et al.; U.S. Pat. No. 5,107,852 to Davidson et al.; U.S. Pat. No. 5,253,653 to Daigle et al.; U.S. Pat. No. 5,345,945 to Hodgson et al.; and U.S. Pat. No. 5,368,049 to Raman et al.
One guide wire type has a distal region which is sufficiently flexible and has a small enough outside diameter to pass into successively smaller and more tortuous coronary vessels. The desired mechanical properties of the guide wire are often met with fabrication from stainless steel or Nitinol, which are largely invisible under fluoroscopy. The small diameter, flexible distal regions are thus difficult to monitor under fluoroscopy, without added radiopacity. Such radiopacity is often provided with radiopaque distal coils.
Guide wires currently have a coil or coils disposed in the distal region, for example, in the distal-most foot of the catheter. A coil is typically formed of a wire wound into a coil and disposed about a guide wire core or shaft. The coil is often wound to meet a close outside diameter dimension specification having a tight tolerance. Single coils often serve as a radiopaque marker. Coils can be made out of radiopaque metal wire, or metal wire that is plated with a more radiopaque metal. The radiopaque coils can be further coated to provide a more lubricous or hemo-compatible surface.
Some guide wires have more than one coil, or a coil formed from more than one segment. In one example, a distal portion of a guide wire has a series of coils disposed over the distal-most foot of the guide wire, to provide a series of markers to allow for taking measurements under fluoroscopy. A series of radiopaque coils, spaced about one centimeter apart, can effectively provide a ruler which is radioscopically visible, and can be used by the treating physician to measure distances within the heart. It may also be desirable to provide coils having different surface properties over the length of the guide wire. For example, it may be desirable to provide more lubricious distal coils and less lubricious proximal coils.
In guide wires having more than one coil, the coils may be affixed to the core wire at each end of each coil. Thus, a guide wire distal portion having four separate affixed coils may require eight welds joining the coil ends to the core wire. What would be desirable are guide wires having multiple coils having varying properties, while requiring the formation, and affixing to core wire, of only a single coil.